Multi-band channel aggregation

ABSTRACT

Multiple channels are aggregated. In an example embodiment, first data is transmitted on a first channel to a wireless device, and second data is simultaneously transmitted on a second channel to the wireless device. The first data and the second data are transmitted in a coordinated manner by aggregating the first channel and the second channel. Various example channel characteristics and combinations thereof are described. Different data allocation options for aggregated channels are described. Other alternative implementations are also presented herein.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/683,314, filed Mar. 7, 2007, now issued as U.S. Pat. No. 8,130,699 onMar. 6, 2012, which is incorporated by reference as if fully set forth.

BACKGROUND

Wireless communication is a virtual necessity in today's society aspeople increasingly use cordless phones, cellular phones, wireless datacommunication devices, and the like on a daily basis. The ability tocommunicate wirelessly has become pervasive in homes, businesses, retailestablishments, and in the outdoors generally. Consequently, people cannow communicate while in transmit and in almost any environment.

Wireless communication involves the use of a limited resource: theelectromagnetic spectrum. Different wireless communication schemesutilize different bands or segments of the electromagnetic spectrum indifferent manners. Typically, each particular segment of theelectromagnetic spectrum is utilized in accordance with a wirelessstandard that has been created by a government entity, an industryconsortium, and/or some other regulatory body.

There are many wireless standards under which wireless devices operatetoday. Example wireless standards include, but are not limited to,Bluetooth, Digital Enhanced Cordless Telecommunications (DECT), CodeDivision Multiple Access (CDMA)-2000, Wideband-CDMA (WCDMA), OrthogonalFrequency Division Multiple Access (OFDMA), Wi-Fi, WiMAX, and so forth.Wireless standards that have a marketing-oriented name typically alsohave a corresponding more technical name for the standard. For example,the term “Wi-Fi” is usually considered to correspond to at least theIEEE 802.11(a), (b), and (g) standards. Similarly, the term “WiMAX” isusually considered to correspond to at least a subset of the IEEE 802.16standard.

A wireless communication device that operates in accordance with any oneof these standards or another standard can generally receive andtransmit electromagnetic signal waves that occupy a portion of thefrequency spectrum. Wireless communication devices are generallydesigned to operate within a particular frequency band so as to avoidinterfering with competing electromagnetic signal waves. Differentfrequency bands offer different advantages and disadvantages forwireless communication. For example, different frequency bands havedifferent propagation and interference characteristics. Moreover, thevarious wireless standards, which generally correspond to an assignedfrequency band or bands, provide for different propagation,interference-resistance, range, throughput, and other characteristics.Generally, no individual frequency band or wireless standard can beoptimum for all communications in all situations.

SUMMARY

In an exemplary embodiment of the invention, first data is transmittedon a first channel to a wireless device. Second data is simultaneouslytransmitted on a second channel to the wireless device such that thefirst data and the second data are transmitted in a coordinated mannerby aggregating the first channel and the second channel. The firstchannel and the second channel are located in different bands. Each ofthe first channel and the second channel is independently and properlyformed so that another wireless device that is unable to support channelaggregation is capable of communicating by independently using one ofthe first channel or the second channel.

In another exemplary embodiment of the invention, respective dataportions are directed toward respective ones of multiple channels basedon respective characteristics of the multiple channels. The respectivedata portions are transmitted to a wireless device on the respectiveones of the multiple channels such that the data portions aretransmitted in a coordinated manner by aggregating the multiplechannels. Each channel of the multiple channels is independently andproperly formed so that another wireless device that is unable tosupport channel aggregation is capable of communicating by independentlyusing one of the multiple channels.

In yet another exemplary embodiment of the invention, first data isdirected toward a first channel based on a first characteristic of thefirst channel. Second data is directed toward a second channel based ona second characteristic of the second channel. The first data istransmitted to a wireless device on the first channel. The second datais simultaneously transmitted to the wireless device on the secondchannel such that the first data and the second data are transmitted ina coordinated manner by aggregating the first channel and the secondchannel. Each of the first channel and the second channel isindependently and properly formed so that another wireless device thatis unable to support channel aggregation is capable of communicating byindependently using one of the first channel or the second channel.

However, other method, system, apparatus, device, media, procedure,arrangement, etc. embodiments for the invention are described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The same numbers are used throughout the drawings to reference likeand/or corresponding aspects, features, and components.

FIG. 1 is a block diagram of an example wireless environment havingmultiple wireless devices and multiple communication links, each ofwhich may include first and second channels.

FIG. 2 illustrates an example wireless environment including first andsecond communication regions that are associated with first and secondcommunication channels, respectively.

FIGS. 3A and 3B illustrate example wireless communication devicesincluding a base station and a subscriber station, respectively, whichcan be utilized to implement embodiments of channel aggregation.

FIGS. 4A and 4B illustrate various components of an example basestation, such as the one shown in FIG. 3A, that can be configured with asingle MAC (FIG. 4A) or multiple MACs (FIG. 4B).

FIG. 5 illustrates an exemplary depiction of communication framestructures for wireless communication via two aggregated communicationchannels for an embodiment of channel aggregation.

FIG. 6 illustrates an example of forming data bursts in downlinksubframes via two aggregated communication channels in an embodiment ofchannel aggregation.

FIG. 7 illustrates an example of zone switching within subframes forwireless communication via two aggregated communication channels for anembodiment of channel aggregation.

FIG. 8 is a flow diagram that illustrates an example method forcommunication transmission using channel aggregation.

FIG. 9 is a flow diagram that illustrates an example method forcommunication reception using channel aggregation.

FIG. 10 illustrates an example wireless environment that includes alicensed communication region and multiple non-exclusively-licensedcommunication regions, and in which embodiments of channel aggregationcan be implemented.

FIG. 11 illustrates examples of channel-aggregated wirelesscommunication in a portion of the environment shown in FIG. 10.

DETAILED DESCRIPTION Channel Aggregation Introduction

Channel aggregation is described for wireless communication in whichexemplary embodiments provide that two or more communication channelscan be channel-aggregated as communication channels, including for asingle service. As described herein, channel aggregation may includetransmitting and receiving data at a wireless communication device ondifferent communication channels in which data from a single service maybe assigned for communication on any one of two or more aggregatedcommunication channels as determined by a channel aggregation system.The channel-aggregated communication channels are each individuallyproperly formed communication channels. The channel-aggregatedcommunication channels can be adjacent channels in the same frequencyband or non-adjacent channels in the same or different frequency bands.

In an exemplary embodiment, a base station operable forchannel-aggregated communication includes a scheduling module that (i)generates a first data set for communication via a first communicationchannel and (ii) generates a second data set for communication via asecond communication channel, where the first data set and the seconddata set each include data intended for transmission to a particularsubscriber station. The base station can also include a first radio totransmit the first data set to the subscriber station via the firstcommunication channel and a second radio to transmit the second data setto the subscriber station via the second communication channel.

In another exemplary embodiment, a subscriber station operable forchannel-aggregated communication includes a first radio to receive afirst data set via a first communication channel, and it includes asecond radio to receive a second data set via a second communicationchannel. The subscriber station can also include a receiving unit with achannel aggregation module that is capable of handlingchannel-aggregated communications. The channel aggregation module is toformulate an integrated data set for a single service from the firstdata set and the second data set.

In one particular example, two different communication channels can be alicensed communication channel and a non-exclusively-licensedcommunication channel. For example, a base station or base stationsystem can be operable for channel-aggregated communication andimplemented in a wireless communication system to transceive data vianon-adjacent, channel-aggregated communication channels that include alicensed communication channel and a non-exclusively-licensedcommunication channel. Similarly, subscriber stations can each beoperable for channel-aggregated communication and implemented in such awireless communication system so as to transceive data via the licensedand the non-exclusively-licensed channel-aggregated communicationchannels.

Although features and concepts of the described systems, methods,devices, media, etc. for channel aggregation can be implemented in anynumber of different environments, communications systems,processing-based systems, structures, and/or other configurations,exemplary embodiments of channel aggregation are described in thecontext of the following example systems and environments.

Channel Aggregation Exemplary Embodiments

FIG. 1 is a block diagram of an example wireless environment 100 havingmultiple wireless devices 102 and 104 and multiple communication links106, each of which may include first and second (or more) channels 110.As illustrated, wireless environment 100 includes a base station 102,one or more networks 108, “n” subscriber stations 104, and “m”communication links 106, with “n” and “m” being the same or differentintegers. Although a single respective communication link 106 is shownas being associated with each respective subscriber station 104, eachsubscriber station 104 may be simultaneously participating in multiplecommunication links 106. By way of example only, a respective first andsecond communication link 106 may correspond to a respective WiMAX andWiFi communication.

Wireless communications environment 100 is representative generally ofmany different types of wireless communications environments, includingbut not limited to those pertaining to wireless local area networks(wireless LANs) (e.g., Wi-Fi or WiMAX technology); wireless wide areanetworks (wireless WANs) (e.g., WiMAX technology); ad hoc wirelessnetworks (e.g., Wi-Fi or Bluetooth technology); cellular technology(including so-called personal communication services (PCS)); trunkingtechnology; metropolitan area networks (MANs), including hybrid ormulti-use (e.g., WiMAX) technology; some combination thereof; and soforth.

In wireless communications environment 100, base station 102 is inwireless communication with subscriber stations 104(1), 104(2) . . .104(n) via wireless communications or communication links 106(1), 106(2). . . 106(m), respectively. Although implementations may vary, basestation 102 is typically fixed, and subscriber stations 104 are usuallymobile, nomadic, or stationary. Although wireless communicationsenvironment 100 depicts base station 102 as communicating with “n”subscriber stations 104 in one general direction, base station 102 mayactually be communicating with any number of subscriber stations 104 inany number of directions, including in different sectors oromni-directionally.

As illustrated, base station 102 is capable of accessing network(s) 108.Network(s) 108 may be one or more of a wired network, another wirelessnetwork, a combination thereof, and so forth. Access to network 108enables base station 102 to forward data from subscriber stations 104 toexternal network locations and vice versa. Network(s) 108 may also beused for backhaul purposes. Examples of network 108 include, by way ofexample but not imitation, the internet, a landline telephone network,another wireless network, wired nodes of the overall network of basestation 102, LANs/WANs/MANs, some combination thereof, etc. that areoperating in accordance with any given communication standard orstandards.

Base station 102 may be, for example, a nexus point, a trunking radio, aswitch or router, an access point, a traditional cellular basetransceiver station, some combination and/or derivative thereof, and soforth. Subscriber stations 104 may be, for example, a hand-held device;a server, client, personal, desktop, and/or laptop computer; a wirelessexpansion card, module, adapter, or similar apparatus that is coupled toa computer or other device; a storage device; a set-top box or othertelevision-related device; a personal digital assistant (PDA); a mobilephone or other mobile appliance; a vehicle having a wirelesscommunication device; a tablet or hand/palm-sized computer; a wirelessrouter; a node of a wireless mesh network; a portable inventory-relatedscanning device; any device capable of processing generally; somecombination thereof; and so forth.

Base station 102 may interact with subscriber stations 104 in accordancewith any individual or combined standardized and/or specialized airinterface technologies. Example air interface technologies include, byway of example but not limitation, an IEEE 802.11 standard, an IEEE802.16 standard, a draft IEEE 802.22 standard, various cellular phonestandards, some combination or derivative thereof, or any other suchtechnology. Applicable wireless schemes include, by way of example butnot limitation, orthogonal frequency division multiple access (OFDMA)schemes, including both time division duplexing (TDD) and frequencydivision duplexing (FDD); orthogonal frequency division multiplexing(OFDM) schemes, including both TDD and FDD; time division-code divisionmultiple access (TD-CDMA) schemes; general frequency division duplexing(FDD) schemes; single carrier (SC) schemes; time division multiplexing(TDM) schemes; some combination thereof; and so forth. Moreover, suchschemes can include those requiring line of sight (LOS) communicationsas well as those allowing non-line of sight (NLOS) communications.

For an exemplary embodiment of channel aggregation, each wirelesscommunication link 106 may be comprised of two or more aggregated(communication) channels 110. As illustrated in particular for wirelesslink 106(m), a single service 112 is being communicated using multipleaggregated channels 110. More specifically, a first channel 110(1) and asecond channel 110(2) are channel-aggregated for communications viawireless link 106(m) for single service 112. Although only two channels110(1) and 110(2) and a single service 112 are explicitly illustrated,channel aggregation may be implemented using any number of two or morecommunication channels and may involve more than one service. In anexample embodiment, integrated data is divided into first data andsecond data. The first data is transmitted on a first channel. Thesecond data is simultaneously transmitted on a second channel such thatthe first data and the second data are transmitted in a coordinatedmanner by aggregating the first channel and the second channel.

First and second aggregated channels 110(1) and 110(2) may each be anytype of channel. They may also share none, one, many, or even allchannel type characteristics. Example channel type characteristicsinclude licensing, adjacency, frequency band, air interface technology,wireless scheme, transmit power, combination(s) thereof, and so forth.Thus, by way of example only, aggregated communication channels may be:licensed or non-exclusively-licensed channels, adjacent or non-adjacentchannels, channels within different frequency bands or channels withinthe same frequency band, channels with the same or different wirelessschemes, and so forth.

For a channel aggregation including a first communication channel 110(1)and a second communication channel 110(2), many combinations ofdifferent channel type characteristics may be implemented. By way ofexample only, the two aggregated channels 110(1) and 110(2) may be: [i]a licensed channel and a non-exclusively-licensed channel, [ii] twolicensed channels in the same band, [iii] two licensed channels indifferent bands, [iv] two non-exclusively-licensed channels in the sameband, [v] two non-exclusively-licensed channels in different bands, andso forth. If the two channels are within the same band, they may beadjacent or non-adjacent.

Phrased differently, two channel-aggregated communication channels 110may be, by way of example only, one of the following seven [7]combinations: [1 and 2] adjacent, same band (either licensed (L) ornon-exclusively-licensed (NEL), but not both); [3 and 4] non-adjacent,same band (either L or NEL, but not both); and [5, 6, and 7]non-adjacent, different bands (L and NEL, L and L, or NEL and NEL).Non-exclusively-licensed channels and bands include those that do notrequire an exclusive license for operation. Examples ofnon-exclusively-licensed channels and bands include, but are not limitedto, those that are lightly-licensed, those that are licensed-exempt, andso forth.

Additionally, channel-aggregated communication channels can be made toappear as independent, properly formed channels such that so-calledlegacy devices can operate using any single communication channel as ifcommunicating with a base station using a communication channel that isnot channel-aggregated. Such legacy devices are not configured tounderstand and/or implement channel aggregation. However, if eachchannel-aggregated communication channel is independent andproperly-formed, the legacy device can not only communicate with thebase station that is implementing channel aggregation, but the legacydevice may also actually communicate with the base station using any oneof the aggregated channels. For example, a first channel and a secondchannel may be properly formed when a subscriber station that is unableto implement channel aggregation is capable of communicating using thefirst channel independently of the second channel.

For example, first and second communication channels may each beproperly formed in accordance with a given wireless standard and/orwireless scheme. Additional examples include, but are not limited to: Aparticular communication channel may be considered properly formed whenthe channel is individually usable by and/or understandable to a legacywireless device that is not designed to implement channel aggregation.Two aggregated communication channels may be considered properly formedif each includes an independent channel mapping. Also, two aggregatedcommunication channels may be considered properly formed if there is aseparate Fast Fourier Transform (FFT) for each aggregated channel. Asanother example, a properly-formed communication channel may entailincluding a preamble and/or one or more gaps (e.g., an uplink/downlinkgap) in accordance with a wireless air interface technology standardand/or wireless scheme.

In an OFDMA wireless network, for instance, two aggregated channels thatare properly formed in accordance with a given OFDMA wireless schemehave separate FFTs. In systems operating in accordance with an OFDMAscheme, each channel usually includes multiple subchannels, with eachsubchannel being comprised of multiple subcarriers. Channel aggregationmay be implemented without using channels that are independent andproperly formed if compatibility with legacy and other devices that donot implement channel aggregation is sacrificed. In suchimplementations, a single FFT can span two channels to therebyeffectively bond them.

FIG. 2 illustrates an example wireless environment 200 including firstand second communication regions 202 and 204 that are associated withfirst and second communication channels 110(1) and 110(2), respectively.As illustrated, wireless environment 200 includes a first communicationregion 202 and a second communication region 204. A first communicationchannel 110(1) is produced in the first communication region 202. Asecond communication channel 110(2) is produced in the secondcommunication region 204.

Both first and second communication regions 202 and 204 are depicted asbeing substantially circular in shape and concentrically positioned.However, either or both regions may have an alternative shape, such as asector, and concentric positioning need not be implemented. Firstcommunication region 202 is depicted as being larger than secondcommunication region 204. However, either region may be larger, or eachregion may be the same size. Second communication region 204 is depictedas being contained within first communication region 202. However,either region may fully or only partially overlap the other. In fact,first and second communication regions 202 and 204 need not overlapsignificantly, if at all, as long as a subscriber station is capable ofsimultaneously communicating via first and second communication channels110(1) and 110(2). Furthermore, a single base station 102 may becreating first and second communication regions 202 and 204 and may betransceiving first and second channel aggregated communications 110(1)and 110(2).

As specifically illustrated in FIG. 2, but by way of example only, abase station (BS) 102 may be realized as a base transceiver station(BTS) 206 or an access point (AP) 208. (As described herein above withparticular reference to FIG. 1, a base station 102 may also be realizedin other manners.) Implementations of base station 102 as a BTS 206 andan AP 208 are illustrated to describe a specific example.

In this specific example, a BTS 206 is associated with firstcommunication region 202. BTS 206 produces first communication channel110(1) and transceives via first communication channel 110(1). An AP 208is associated with second communication region 204. AP 208 producessecond communication channel 110(2) and transceives via secondcommunication channel 110(2). A single subscriber station 104 maysimultaneously communicate with AP 208 over second communication channel110(2) and with BTS 206 over first communication channel 110(1) in achannel-aggregated scenario. Each of first and second aggregatedcommunication channels 110(1) and 110(2) are properly-formed such that awireless device that is unable to understand and/or interoperate withchannel aggregation can still share either of first communicationchannel 110(1) or second communication channel 110(2).

In a particular exemplary embodiment, first communication region 202 isdesignated for licensed communications, and second communication region204 is designated for non-exclusively-licensed communications. Hence, insuch an embodiment, first communication channel 110(1) may be part of alicensed communication band, and second communication channel 110(2) maybe part of a non-exclusively-licensed communication band. More detailedexemplary embodiments involving licensed and non-exclusively-licensedchannel-aggregated communications are described herein below withparticular reference to FIGS. 10 and 11.

FIGS. 3A and 3B illustrate example wireless communication devicesincluding a base station 102 and a subscriber station 104, respectively,which can be utilized to implement embodiments of channel aggregation.Base station 102 and subscriber station 104 may be considered wirelesscommunication devices generally. As illustrated, each of base station102 and subscriber station 104 include one or more input/output (I/O)interfaces 302, at least one transceiving unit 304, at least oneprocessor 306, and one or more processor-accessible media 308. Media 308includes processor-executable instructions 310, examples of which mayinclude, but are not limited to, an operating system 312 and one or moreapplication programs 314.

In a described implementation, I/O interfaces 302 enable communicationthrough wired media and/or a (e.g., secondary) wireless interface.Generally, processor 306 is capable of executing, performing, and/orotherwise effectuating processor-executable instructions, such asprocessor-executable instructions 310. Media 308 is comprised of one ormore processor-accessible media. In other words, media 308 may includeprocessor-executable instructions 310 that are executable by processor306 to effectuate the performance of functions by base station 102 orsubscriber station 104.

Thus, realizations for channel aggregation may be described in thegeneral context of processor-executable instructions. Generally,processor-executable instructions include programs, applications,coding, modules, objects, interfaces, components, data structures, etc.that perform and/or enable particular tasks and/or implement particularabstract data types. Processor-executable instructions may be located inseparate storage media, executed by different processors, and/orpropagated over or extant on various transmission media. Moreover,processor-executable instructions may be embodied as software, firmware,hardware, fixed logic circuitry, some combination thereof, and so forth.

Processor(s) 306 (e.g., any of microprocessors, controllers, etc.) maybe implemented using any applicable processing-capable technology. Media308 may be any available media that is included as part of and/oraccessible by base station 102 or subscriber station 104. It includesvolatile and non-volatile media, removable and non-removable media,storage and transmission media (e.g., wireless or wired communicationchannels), hard-coded logic media (e.g., an application-specificintegrated circuit (ASIC), a field programmable gate-array (FPGA),etc.), and so forth. Media 308 is tangible media when it is embodied asa manufacture and/or a composition of matter. By way of example only,media 308 may include an array of disks or flash memory for longer-termmass storage of processor-executable instructions, random access memory(RAM) for shorter-term storing of instructions that are currently beingexecuted and/or otherwise processed, link(s) on networks fortransmitting communications, and so forth.

FIG. 3A illustrates an example base station 102. With base station 102,I/O interfaces 302 provide access to other networks, such as network(s)108 (of FIG. 1). Network 108 may be a backhaul network for the wirelessnetwork. Base station 102 also includes a transmitting unit 304(T)and/or a receiving unit 304(R), which may be termed a transceiving unit304 (not separately shown). Transceiving unit 304 enables base station102 to communicate wirelessly via communication links 106. Transmittingunit 304(T) and receiving unit 304(R) may include one or more, andusually multiple, transmitters or receivers, respectively, and/or one ormore transmitting chains or receiving chains. Each transmitter andreceiver may include one or more radios (not explicitly shown) that arededicated or shared.

With base station 102, processor-executable instructions 310 areillustrated as including a medium access controller (MAC) 316, ascheduler 318, and a BS channel aggregation module 320. In a describedimplementation, MAC 316 plans, orders, regulates, and otherwise controlsaccess to the wireless medium. Scheduler 318 interacts with a quality ofservice (QoS) engine (not shown) to determine which services are duesome portion of the available bandwidth of the wireless medium.Scheduler 318 may be part of MAC 316. Different implementations having asingle MAC or multiple MACs are described herein below with particularreference to FIG. 4.

BS channel aggregation module 320 is responsible for the functions thatenable implementation of channel aggregation for two or more channels.In manners that are apparent from the description herein, BS channelaggregation module 320 interacts with MAC 316 and/or scheduler 318 inthe performance of some of these channel aggregation functions. Forexample, during transmission, the division of data between two differentaggregated communication channels is determined. During reception, datareceived on two different aggregated communication channels isrecombined into joint or integrated data, perhaps for a single service.

BS channel aggregation module 320 is also at least partially responsiblefor announcing that base station 102 is capable of aggregating two ormore channels. For example, this announcement may be in the form of ageneral broadcast throughout its associated communication region.Alternatively, the announcing may be in the form of a capabilitiesnegotiation with individual subscriber stations, especially with thosethat indicate they are capable of channel aggregation.

FIG. 3B illustrates an example subscriber station 104. With subscriberstation 104, I/O interfaces 302 provide access through ingress and/oregress ports to data source(s) and/or sink(s) 352. Data sources andsinks 352 may include, for example, a local processing device or memory,a man-machine interface (e.g., keyboard/keypad, speaker, microphone,etc.), a network connection, and so forth. Hence, I/O interfaces 302 forsubscriber station 104 may be any one or more of a serial and/orparallel interface, a universal serial bus (USB) interface, a wirelessinterface, a network interface, or any other type of interface forexternal communication. Examples include, by way of example but notlimitation, a network interface card (NIC), a modem, one or more networkports, some combination thereof, and so forth.

Subscriber station 104 also includes a transmitting unit 304(T) and/or areceiving unit 304(R), which may be termed a transceiving unit 304 (notseparately shown). Transceiving unit 304 enables subscriber station 104to communicate wirelessly via communication links 106. Transmitting unit304(T) and receiving unit 304(R) may include one or more transmitters orreceivers, respectively, and/or one or more transmitting chains orreceiving chains. Having multiple (e.g., at least two) receiving chainsand transmitting chains enables a subscriber station 104 to participatein a channel-aggregated wireless communication. Each transmitter andreceiver may include one or more radios (not explicitly shown) that arededicated or shared.

With subscriber station 104, processor-executable instructions 310 areillustrated as including a SS channel aggregation module 354. In adescribed implementation, SS channel aggregation module 354 is at leastpartially responsible for handling channel aggregated communications andperforming the SS-side functions of channel aggregation as describedherein. For example, SS channel aggregation module 354 is capable ofdividing data over aggregated channels during transmission and combiningdata into joint or integrated data from two or more aggregated channelsduring reception. Although not so illustrated specifically, a subscriberstation 104 may also include a MAC and/or a scheduler.

SS channel aggregation module 354 is also capable of requesting oraccepting channel aggregated communications with a base station. Forexample, SS channel aggregation module 354 may detect a broadcastnotification that a given base station is capable of implementingchannel aggregation. Also, SS channel aggregation module 354 may notifya base station of a channel-aggregating capability during a capabilitiesnegotiation.

FIGS. 4A and 4B illustrate various components of an example basestation, such as the one shown in FIG. 3A, that can be configured with asingle MAC (FIG. 4A) or multiple MACs (FIG. 4B). A single MACconfiguration 316(S) is illustrated in FIG. 4A. A multiple MACconfiguration 316(M) is illustrated in FIG. 4B. Each of the illustratedboxes may represent modules and/or applications of processor-executableinstructions 310.

Single MAC configuration 316(S) includes independent physical layers402(1) and 402(2) for first aggregated channel 110(1) and secondaggregated channel 110(2), respectively. A physical layer 402 caninclude various components, such as a transceiving unit 304 (of FIG. 3),filtering components, and other components to receive and transmitwireless data. Single MAC configuration 316(S) also includes anaggregation layer 404, a convergence sublayer 406, and a single MAC316*. In this single MAC configuration, MAC 316* can include scheduler318.

In single MAC configuration 316(S), the single MAC 316* is implementedto map the data to the physical resources or to respond to requests bythe base station in the uplink. This typically involves an awareness ofQoS, destination, state of the physical resources, and so forth. Itshould be understood that the term “single MAC” refers to two or morechannels 110/physical layers 402 in a particular channel-aggregation; agiven base station may implement a single MAC configuration 316(S)repeatedly for different sectors, different frequency bands, and soforth.

Multiple MAC configuration 316(M) includes independent physical layers452(1) and 452(2) for first aggregated channel 110(1) and secondaggregated channel 110(2), respectively. Multiple MAC configuration316(M) also includes a respective independent MAC 316(1) and 316(2)corresponding to each respective physical layer 452(1) and 452(2). Themultiple MAC configuration also includes an aggregation layer 454 and aconvergence sublayer 456, which includes scheduler 318. In multiple MACconfiguration 316(M), MACs 316(1) and 316(2) are implemented to performmany of the same functions as the single MAC 316*. It should beunderstood that scheduler 318 need not be moved out of the MACs 316(1)and 316(2) to implement multiple MAC configuration 316(M). In fact,scheduler 318 is moved to convergence sublayer 456 if a single serviceis to be split across multiple physical layers 452. If the split is tobe performed on a per-service basis rather than on a per-packet basis,scheduler 318 is located in each MAC 316(1) and 316(2) and convergencesublayer 456 then directs the packets for a particular service to aparticular MAC 316(1) or 316(2) without truly “scheduling” them.

However, because the decision regarding what channel a packet istransmitted on has already been made (e.g., at convergence sublayer 456)in multiple MAC configuration 316(M), independent MACs 316(1) and 316(2)do not perform that aspect of scheduling. In other words, with multipleMAC configuration 316(M), some aspects of scheduling are performed atconvergence sublayer 456 while other scheduling aspects are performed atMACs 316. Consequently, independent MACs 316(1) and 316(2) cannot becreative regarding the routing of data based on QoS. This occurs in theconvergence sublayer/aggregation modules. It also means that sendingautomatic retransmit request (ARQ) retries or ACKs on a differentchannel is not feasible with independent MACs 316(1) and 316(2). Inshort, with multiple MAC configuration 316(M), some of the complexity ofscheduling is split between convergence sublayer 456 and MACs 316(1) and316(2) at the expense of features/flexibility. For example, withmultiple MAC configuration 316(M), a single service cannot easily besplit between the two physical layers 452(1) and 452(2).

One skilled in the art would understand how to implement layers 402,404, and 406 (and corresponding layers 452, 454, and 456 of FIG. 4B) aswell as the overall single MAC configuration 316(S) (and multiple MACconfiguration 316(M)) in view of the descriptions and teachings herein.Nevertheless, abbreviated descriptions of the aggregation layer and theconvergence sublayer are provided below.

Aggregation layer 404/454 is relatively thin. It directs the datato/from the correct channel. In single MAC configuration 316(S),aggregation layer 404 is the realization of arrows 614 between the burstconstruction queues 606/608/610 and the subframe structures 504/508 inFIG. 6, which is described herein below. Convergence sublayer 406/456determines which subscriber station a packet goes to and on whichconnection. The next layer down then uses that determination to performits function. In single MAC configuration 316(S), convergence sublayer406 passes its information to MAC 316* for scheduling at scheduler 318.In multiple MAC configuration 316(M), convergence sublayer 456 passesits information to the correct MAC 316(1) or 316(2).

FIG. 5 illustrates an exemplary depiction of communication framestructures 504, 506, 508, and 510 for wireless communication via twoaggregated communication channels 502(1) and 502(2) for an embodiment ofchannel aggregation. First and second communication channels 502(1) and502(2) are specific examples of general first and second communicationchannels 110(1) and 110(2) (of FIG. 1). First aggregated communicationchannel-A 502(1) includes a downlink (DL) subframe 504 and an uplink(UL) subframe 506. Second aggregated communication channel-B 502(2)includes a DL subframe 508 and an UL subframe 510.

Wireless data for communication with various subscriber stations 1-8 (SS1-SS 8) can be tiled for OFDMA to define a relationship between twoframes that are transmitted simultaneously on the two aggregatedcommunication channels 502(1) and 502(2). In this example, data forsubscriber stations 3 and 6 (SS 3 and SS 6) are enabled for channelaggregated operation, and data for the other subscriber stations (i.e.,SS 1, 2, 4, 5, 7, and 8) are enabled for single channel operation.Although the illustrated frame structures comport with an IEEE 802.16(e)wireless standard implementing TDD OFDMA, the principles are applicableto other air interface technologies and wireless schemes.

In addition to downlink data for the subscriber stations 1-8 (SS 1-8),DL subframes 504 and 508 each include respective preambles 512(1) and512(2), respective DL maps 514(1) and 514(2), and respective UL maps516(1) and 516(2). In addition to uplink data for the subscriberstations 1-8 (SS 1-8), UL subframes 506 and 510 each include a rangingsubchannel. Each data burst shown in the subframe structures may containone or more data packets and/or data packet fragments.

Subscriber station 3 (SS 3) is associated with a number of bursts insubframes 504, 506, 508, and 510. First aggregated communicationchannel-A 502(1) includes downlink data for subscriber station 3 (SS 3)at “DL Burst 3A”, as indicated at 518. Second aggregated communicationchannel-B 502(2) includes downlink data for subscriber station 3 (SS 3)at “DL Burst 1B”, as indicated at 520. First aggregated communicationchannel-A 502(1) includes uplink data from subscriber station 3 (SS 3)at “UL Burst 3A”, as indicated at 522. Second aggregated communicationchannel-B 502(2) includes uplink data from subscriber station 3 (SS 3)at “UL Burst 1B”, as indicated at 524.

Channel aggregation modules 320 and 354 (of FIGS. 3A and 3B) areresponsible for dividing integrated data into two or more sets that arebeing transmitted across two or more aggregated channels and forcombining the data sets that are being received via the two or moreaggregated channels into the integrated data. For example, integrateddata for subscribe station 3 (SS3) is divided into first data of “DLBurst 3A” 518 and second data “DL Burst 1B” 520 at a base station. Atsubscriber station 3, the first data of “DL Burst 3A” and the seconddata of “DL Burst 1B” are combined into the integrated data.

As illustrated in FIG. 5, there can be substantial variability in themapping of data due to the nature of data traffic, such as IP datatraffic. For instance, some subscriber stations may not receive data inevery frame, or they may have asymmetric uplink and downlink needs, notonly on the average, but also instantaneously on a frame by frame basis.Moreover, there is an additional variability caused by changingparameters at the physical layer. For example, the same data amount maytake more or less absolute bandwidth from time to time as conditions ofthe physical layer vary as a result of how these conditions can impactavailable modulation and coding rate options. Base station 102 schedulesthe bandwidth taking this into account by scheduling the transmission ofactual data in the downlink and by scheduling logical demand in theuplink.

FIG. 5 illustrates an example for how channel aggregation may beimplemented in an IEEE 802.16 OFDMA-based system that is operating witha TDD mechanism. However, a FDD mechanism is also effective in an OFDMAsystem. Moreover, channel aggregation as described herein can be appliedto SC, TD-CDMA, and other wireless communication schemes that areidentified herein.

FIG. 6 illustrates an example 600 of forming data bursts in downlinksubframes 504 and 508 via two aggregated communication channels 502(1)and 502(2) in an embodiment of channel aggregation. In this illustratedexample of data burst formation 600, scheduler 318 (of FIG. 3) dividesthe subscriber stations 1-8 (SS 1-8) into three groups 602(1, 2, 3).Group 602(1) includes those subscriber stations (e.g., SS 1, 2, 4, and5) that are implemented only for single channel operation and that haveaccessed the network on first communication channel 502(1). Group 602(2)includes those subscriber stations (e.g., SS 7) that are implementedonly for single channel operation and that have accessed the network onsecond communication channel 502(2).

Group 602(3) includes those subscriber stations (e.g., SS 3 and 6) thatare currently operable for channel aggregated operation on both firstand second communication channels 502(1) and 502(2). In this example,first communication channel 502(1) may therefore be considered to befunctioning as a standard single communication channel with respect tosubscriber stations 1, 2, 4, and 5 but as a aggregated communicationchannel with respect to subscriber stations 3 and 6.

Data for the three separate groups 602(1, 2, and 3) of subscriberstations have respective separate class queues 604(1, 2, and 3). Theseclass queues 604 may be part of a QoS engine (not shown) that isassociated with scheduler 318 of MAC 316 (all of FIG. 3A). The QoSengine runs initially over the three groups of queues 604(1-3) toextract data based on at least one fairness algorithm that has beenimplemented. In this example, data from group 602(1) isallocated/directed from burst construction queue 606 to first singlecommunication channel 502(1) at aggregation layer arrow 614(1), and datafrom group 602(2) is allocated/directed from burst construction queue608 to second single communication channel 502(2) at aggregation layerarrow 614(2). Data from group 602(3) can be allocated/directed fromburst construction queue 610 to either one or a combination of first andsecond aggregated communication channels 502(1) and 502(2) ataggregation layer arrow 614(3).

If the downlink subframe 504 or 508 for either of the first and secondcommunication channels 502(1) or 502(2) is individually fully allocatedbefore the combination of communication channels 502(1) and 502(2) hasbeen fully allocated, the QoS engine or scheduler 318 closes a gate612(1) or 612(2) for the group 602(1) or 602(2), respectively, thatcorresponds to the communication channel 502(1) or 502(2) having afully-allocated DL subframe. The QoS engine can continue allocatinguntil the combination of data from all three groups 602(1-3) fills bothcommunication channels 502, or until the time limit for filling theframe has expired. The result is a DL subframe 504 with data from group602(1) in first communication channel 502(1) and a DL subframe 508 withdata from group 602(2) in second communication channel 502(2). Both DLsubframe 504 and DL subframe 508 may have data from group 602(3) becausethe data in class queue 604(3) is distributed over both firstcommunication channel 502(1) and second communication channel 502(2).

FIG. 7 illustrates an example of zone switching 700 within subframes704, 706, 708, and 710 for wireless communication via two aggregatedcommunication channels 702 for an embodiment of channel aggregation.First aggregated communication channel-A 702(1) includes a DL subframe704 and an UL subframe 706. Second aggregated communication channel-B702(2) includes a DL subframe 708 and an UL subframe 710. First andsecond aggregated communication channels 702(1) and 702(2) are specificexamples of general first and second communication channels 110(1) and110(2) (of FIG. 1).

Although not required to implement channel aggregation, zone switching700 may be employed in conjunction with two or more aggregatedcommunication channels 702 to form a clear demarcation between zoneswith channel aggregation and zones without. Thus, in a describedimplementation, a new zone definition provides that the DL and ULsubframes can be segregated into zones that are channel aggregated andzones that are not. For example, zone switches 712 are shown in firstaggregated communication channel-A 702(1) and second aggregatedcommunication channel-B 702(2).

As illustrated, there are three groups: Group 1 (channel A only), Group2 (channel B only), and Group 3 (channels A and B), with Group 3corresponding to the channel-aggregated zones. Zone switch 712(1-UL)segregates UL subframe 704 of first aggregated communication channel-A702(1) into a Group 1 zone and a Group 3 zone. Zone switch 712(1-DL)segregates DL subframe 706 of first aggregated communication channel-A702(1) into a Group 1 zone and a Group 3 zone. Zone switch 712(2-UL)segregates UL subframe 708 of second aggregated communication channel-B702(2) into a Group 2 zone and a Group 3 zone. Zone switch 712(2-DL)segregates DL subframe 710 of second aggregated communication channel-B702(2) into a Group 2 zone and a Group 3 zone.

As shown by dashed lines 714, the zone switches 712 may occur atdifferent times (or frequencies) in each subframe on each communicationchannel 702. Also, the temporal (or frequency) location of the zoneswitches may be adjusted based on demand. For example, zone switching700 can be adjusted frame to frame based on the relative demand and QoSconstraints of data traffic between channel aggregation and non-channelaggregation subscriber stations. Although not so illustrated, thechannel-aggregated zone or zones can precede the non-channel-aggregatedzone or zones in any or all of the subframes. Moreover, there can bemore or less than the two zones illustrated, and there can be differentnumbers of zones (including one/none) in different subframes of the samechannel or aggregated channels. Furthermore, zone segregation can beperformed along a temporal dimension and/or a frequency dimension (e.g.,using sets of subcarriers).

FIGS. 8 and 9 are flow diagrams 800 and 900, respectively, illustratingexample methods related to implementing channel aggregation. Flowdiagram 800 includes three (3) blocks 802-806, and flow diagram 900includes three (3) blocks 902-906. Implementations of these flowdiagrams 800 and 900 may be realized, for example, asprocessor-executable instructions 310. The actions of flow diagrams 800and 900 may be performed in many different environments and with avariety of wireless communication devices, including by a base station102 or a subscriber station 104 (both of FIGS. 1, 3A, and 3B). Exampleimplementations for flow diagrams 800 and 900 that are described belowalso refer to other FIGS. that are described elsewhere herein. The orderin which the methods are described is not intended to be construed as alimitation, and any number of the described blocks can be combined,augmented, rearranged, and/or omitted to implement a respective method,or an alternative method that is equivalent thereto.

FIG. 8 is a flow diagram 800 that illustrates an example method forcommunication transmission using channel aggregation. At block 802, atleast two communication channels are aggregated for wireless datacommunication, with the two communication channels including a firstaggregated communication channel and a second aggregated communicationchannel. For example, a first communication channel 110(1) may beaggregated to a second communication channel 110(2) (of FIG. 1).

Example communication channel characteristics and communication channelcombinations are presented. Communication channels 110(1) and 110(2) maybe adjacent or non-adjacent. Non-adjacent channels may be in the samefrequency band or in different bands. Two aggregated communicationchannels 110 may be any of the following combinations: licensed (L) andnon-exclusively-licensed (NEL), both L, both NEL, and so forth.Furthermore, additional embodiments of channel aggregation may includeany two or more aggregated communication channels that have a disparityin transmission power regulation, filtering, or other differences. Otherchannel characteristics and combinations may alternatively beimplemented.

At block 804, integrated data is divided for data communication via thefirst and second channel-aggregated communication channels. For example,data for a single service 112 may be divided (as at burst constructionqueue 610) into first data for first communication channel 502(1) andsecond data for second communication channel 502(2) (of FIG. 6). Forinstance, integrated data for subscriber station 3 (SS 3) may be dividedinto a first data set for “DL Burst 3A” and a second data set for “DLBurst 1B”, as is illustrated in FIG. 6. Although an individualsubscriber station 104 need not address communications for multipleother subscriber stations 104, each subscriber station 104 that isparticipating in a channel-aggregated communication can divide itsintegrated data into multiple data sets for multiple respectivechannel-aggregated communication channels, prior to transmission.

At block 806, first data is transmitted via the first aggregatedcommunication channel and second data is transmitted via the secondaggregated communication channel. For example, first data (e.g., “DLBurst 3A” for SS 3 of FIG. 6) may be transmitted via first aggregatedcommunication channel 502(1), and second data (e.g., “DL Burst 1B”) maybe transmitted via second aggregated communication channel 502(2).

In a particular example embodiment, the first data and the second datamay be communicated using an OFDMA scheme via non-adjacent,channel-aggregated communication channels. The first data may betransmitted, for instance, via a licensed communication channel for arelatively high quality of service, and the second data may besimultaneously transmitted via a non-exclusively-licensed communicationchannel for best-effort data communication.

FIG. 9 is a flow diagram 900 that illustrates an example method forcommunication reception using channel aggregation. At block 902, firstdata is received via a first aggregated communication channel, andsecond data is received via a second aggregated communication channel.For example, first data (e.g., “DL Burst 3A” for SS 3 of FIG. 6) may bereceived via a first aggregated communication channel 502(1) whilesecond data (e.g., “DL Burst 1B”) may be simultaneously received via asecond aggregated communication channel 502(2).

Although the examples given for FIGS. 8 and 9 refer to a downlinkaggregated channel communication, they are also applicable to an uplinkaggregated channel communication. In other words, a subscriber stationcan also implement the actions of flow diagram 800, and a base stationcan also implement the actions of flow diagram 900.

At block 904, the first data and the second data are combined intointegrated data. For example, the first data and the second data may becombined into integrated data for a single service 112 at a receivingsubscriber station 104 (or base station 102).

At block 906, the first data and the second data are ordered inaccordance with a predefined ordering scheme. For example, the firstdata and the second data of each burst may be received in any order,including fully or partially simultaneously. The first and second datasets are thus reordered so as to maintain the intended meaning andcoherency of the original integrated data. In other words, the order ofthe integrated data prior to its division at a transmitting wirelesscommunication device is restored at a receiving wireless communicationdevice.

Generally, a given ordering scheme may be applied at the transmittingwireless device and/or the receiving wireless device. An ordering schememay be a predefined default ordering, a numbering sequence protocolincluded with the data, and so forth. By way of example only, anumbering sequence protocol may entail data that is ordered according toan automatic retransmit request (ARQ) numbering sequence protocol thatis already included along with the data in some wireless communicationschemes. Alternatively, or in addition, the data packets can be orderedaccording to a special channel-aggregated numbering sequence that isannotated to the data.

More specifically, for a default ordering scheme, all of the datareceived on a first aggregated channel can be considered logicallyearlier in a data communication sequence than data received on a secondchannel, irrespective of which data arrives earlier or a simultaneousarrival on the first and second channels. Also, if the division betweenaggregated channels is performed on an entire service basis (e.g., alldata of one service for a particular subscriber station is sent over afirst channel, and all data of another service for the particularsubscriber station is sent over a second channel), there is no numberingproblem. In general, a predefined ordering scheme is applicable forthose services that can have data packets for the same service takedifferent paths. However, a priori knowledge that at least one higherlayer already has an order preservation scheme can be used to simplifyordering for data that has been divided for channel aggregation.

For a numbering sequence protocol scheme, data can be ordered by aspecial channel-aggregating numbering sequence that annotates the datawith a channel ordering indicator when communicated via thechannel-aggregated communication channels. Alternatively, the data canbe ordered using the ARQ numbering sequence protocol when the data iscommunicated via channel-aggregated communication channels. An ARQ isalso commonly referred to as an automatic “resend” request or anautomatic “repeat” request. ARQ is a protocol for error control whentransmitting data. When a receiving device detects a corrupt datapacket, it can automatically request that a transmitting device resendthe data packet using the ARQ sequence number. Consequently, an ARQsequence number can be used for data packet sequence numbering withdivided data that is received over two or more aggregated channels, aswell as to detect corrupt or missing data. Alternatively, if a highernetwork layer or level is already known to include a numbering sequenceprotocol, the numbering from the higher network layer or level may berelied on to maintain an intended order with multiple aggregatedchannels.

With reference again to FIG. 2, a specific example is illustrated asdescribed in detail herein above. In this specific example, a BTS 206 isassociated with a first communication region 202. BTS 206 transceivesvia first communication channel 110(1). An AP 208 is associated with asecond communication region 204. AP 208 transceives via secondcommunication channel 110(2). FIGS. 10 and 11 illustrate a moreparticular example in which first communication region 202 correspondsto a licensed communication region and second communication region 204corresponds to a non-exclusively-licensed region. This particularexample, without loss of generality, is used to describe other generalprinciples and alternatives of channel aggregation.

FIG. 10 illustrates an example wireless environment 1000 that includes alicensed communication region 202 and multiple non-exclusively-licensedcommunication regions 204, and in which embodiments of channelaggregation can be implemented. By way of example only, the descriptionof FIGS. 10 and 11 refers to region 202 as a cell. Thus, wirelessenvironment 1000 includes a licensed communication cell 202 and multipleoverlapping non-exclusively-licensed communication regions 204(1-N) thatare positioned or located substantially within cell 202.

Wireless communication throughout licensed communication cell 202 isfacilitated by BTS 206 that communicates (e.g., transmits and/orreceives) data for wireless communication. Each non-exclusively-licensedcommunication region 204 includes a respective wireless AP 208(1-N) thatfacilitates wireless communication within the respectivenon-exclusively-licensed communication region 204(1-N).

BTS 206 and each of APs 208(1-N) can be implemented to operate in achannel aggregated mode in which wireless data is communicated viachannel-aggregated communication channels. For example, BTS 206 cancommunicate data for wireless data communication in which a first dataset is transmitted via a licensed communication channel (within licensedcommunication cell 202) while a second data set is simultaneouslytransmitted by at least one AP 208 via a non-exclusively-licensedcommunication channel (within at least one non-exclusively-licensedcommunication region 204). As is described more fully herein below,utilizing non-exclusively-licensed communication regions 204(1-N) canincrease overall capacity (e.g., bandwidth) and/or improve diversitygain for wireless data communication, depending on whether differentsignals or the same signals, respectively, are transmitted withinregions 204(1-N).

In example wireless environment 1000, non-exclusively-licensedcommunication regions 204(1-N) may tend to have a lower allowabletransmit power and/or other constraints that are commonly imposed onjointly-used spectrum bands. They are also likely subject to increasedcommunication interference. For increased diversity gain, APs 208(1-N)in their respective non-exclusively-licensed communication regions204(1-N) can therefore each be implemented so as to communicate the samedata between subscriber stations and the wireless system. In otherwords, each of the APs 208(1-N) that receives data from the wirelesssystem can transmit it on the same non-exclusively-licensedcommunication channel to subscriber stations within wirelesscommunication range. Hence, a targeted subscriber station canpotentially receive multiple versions of the same communication frommultiple APs 208, especially when the targeted subscriber station is inan overlapping region such as boundary region 1010. Thenon-exclusively-licensed communication channel of APs 208 can beaggregated to a licensed communication channel being used by BTS 206.

FIG. 11 illustrates examples of channel-aggregated wirelesscommunication in a portion of the environment 1000 that is shown in FIG.10. The portion shown in FIG. 11 illustrates part of an example wirelesscommunication system 1100 having multiple wireless devices includingsubscriber stations 104, a BTS 206, and multiple APs 208, as well as adata combiner 1104. As illustrated, wireless communication system 1100includes licensed communication cell 202 and BTS 206 that cancommunicate (e.g., transmit and/or receive) data for wireless datacommunication. Wireless communication system 1100 also includesnon-exclusively-licensed communication regions 204(1-3, N) andrespective APs 208(1-3, N) that are within the portion of wirelessenvironment 1000 (of FIG. 10) that is illustrated in FIG. 11.

Wireless communication system 1100 includes examples of subscriberstations 104(1-2) that can each communicate (e.g., transmit and/orreceive) data for wireless data communication within licensedcommunication cell 202 and/or within one or more ofnon-exclusively-licensed communication regions 204. By way of exampleonly, subscriber station 104(1) is illustrated as a laptop computer, andsubscriber station 104(2) is illustrated as an intelligent mobile phoneand/or wireless PDA.

Various communication links 106 are shown between (i) BTS 206 and APs208(1-3) and (ii) subscriber stations 104(1-2) to illustratechannel-aggregated wireless communication between the wireless devices.For example, subscriber station 104(2) can communicate first data withBTS 206 via a licensed communication link 106(2-A) that represents achannel-aggregated licensed communication channel. Subscriber station104(2) can also simultaneously communicate second data with AP 208(1)via a non-exclusively-licensed communication link 106(2-B) thatrepresents a channel-aggregated non-exclusively-licensed communicationchannel.

In this example with subscriber station 104(2), a first aggregatedcommunication channel 110(1) (of FIG. 1) corresponds to communicationlink 106(2-A), and a second aggregated communication channel 110(2)corresponds to communication link 106(2-B). Somewhere within wirelesscommunication system 1100, aggregated communication channels 110(1) and110(2) are combined, possibly for a single service 112. This isdescribed further below with regard to subscriber station 104(1).

In the context of channel aggregation, simultaneous communication on two(or more) communication links 106 and/or two (or more) aggregatedchannels 110 (of FIG. 1) implies that communication is occurring at thesame moment (e.g., during the same burst periods, frames, subframes,and/or time periods, etc.) at least part of the time. It should berecognized that there are other moments when transceiving may only beoccurring on one of the aggregated communications just as their willlikely be instantaneous moments when there is no transceiving on any ofthe aggregated communications, at least with air interface technologiesinvolving some time division of the medium. Consequently, from time totime, certain portions of the first data may arrive prior to portions ofthe second data, or vice versa.

As another example in wireless communication system 1100, subscriberstation 104(1) can communicate a first data set with BTS 206 via alicensed communication link 106(1-A) that represents achannel-aggregated licensed communication channel. Subscriber station104(1) can also simultaneously communicate a second data set with AP208(2) via a non-exclusively-licensed communication link 106(1-B-i)and/or with AP 208(3) via a non-exclusively-licensed communication link106(1-B-ii), each of which represents a channel-aggregatednon-exclusively-licensed communication channel.

In this example with subscriber station 104(1), a first aggregatedcommunication channel 110(1) (of FIG. 1) corresponds to communicationlink 106(1-A), and a second aggregated communication channel 110(2)corresponds to communication link 106(1-B-i) and/or communication link106(1-B-ii). For this example, it is given that each AP 208(1-N) istransceiving the same data. Thus, the second data set received via bothcommunication link 106(1-B-i) and communication link 106(1-B-ii) can becombined using a diversity combining mechanism.

In order to perform this diversity combining, the two versions of thesecond data set are forwarded to data combiner 1104 via links 1102(2)and 1102(3). Data combiner 1104 may be located at a centralizedlocation, at BTS 206, at an AP 208, or any other location accessible bywireless communication system 1100. These links 1102 may be wirelesslinks or wired links. When wireless communication system 1100 istransmitting to a subscriber station 104, a data divider or splitterthat is analogous to data combiner 1104 is employed.

With channel aggregation generally, the first data set received viacommunication link 106(1-A) and the second data set received viacommunication link 106(1-B) are combined to form integrated data at datacombiner 1104. This combination may be performed as part of a channelaggregation module (e.g., BS channel aggregation module 320) that islocated anywhere within wireless communication system 1100, includingsome centralized data processing facility. This data combination isillustrated generically as data combiner 1104. The data combination fordiversity combining and the data combination for channel aggregation maybe performed at the same location or at different locations. (For asubscriber station 104, channel aggregation data combining may beperformed by SS channel aggregation module 354.)

With channel aggregation data combination, the first data set and thesecond data set are forwarded (e.g., using a backhaul version of network108) to one location for combining into the integrated data. By way ofexample only, the second data set can be forwarded from AP(s) 208 usinglinks 1102 to BTS 206. In this case, links 1102 may be realized as awireless signal (including a copied signal that results in APsperforming a relay function), a wired signal, a point-to-point microwavesignal, some combination thereof, and so forth. If the first data set isforwarded to a third location for combining, a wireless or wired link(not separately shown) from BTS 206 that is analogous to links 1102 maybe used.

By way of example only, data can be communicated between (i) BTS 206 andAPs 208 (1-3, N) and (ii) subscriber stations 104(1-2) in apoint-to-multipoint fashion utilizing OFDMA via the channel aggregatedcommunication channels. The IEEE 802.16 standard is one example of astandard that supports OFDMA systems. Other examples include, but arenot limited to, asymmetric digital subscriber line (ADSL) systems, somebroadband wireless access systems (e.g., draft standard IEEE 802.22),contemplated 4th Generation (4G) wireless standards (which may includeIEEE 802.16), and so forth.

In an example embodiment, channel-aggregating a licensed communicationchannel and a non-exclusively-licensed communication channel for datacommunication can take advantage of the non-exclusively-licensedspectrum to effectively increase available bandwidth by an order ofmagnitude over competitors that may have similar licensed communicationspectrums. Further, the aggregated licensed and non-exclusively-licensedcommunication channels need not be the same width to implement channelaggregation. For example, a 5 MHz licensed communication channel fromthe WCS band can be aggregated with a 6 MHz non-exclusively-licensedcommunication channel using unused television signal spectrum, or it canbe aggregated with a 10 MHz non-exclusively-licensed communicationchannel.

Efficiency, improved service, etc. can be gained for wireless datacommunication when data is communicated via channel-aggregatedcommunication channels. For example, first data having a higher qualityneed, such as voice or other real-time data, can be transmitted via arelatively higher quality aggregated channel, and second data which issuitable for best efforts can be transmitted via a relatively lowerquality aggregated channel. Typically, but not universally, a licensedcommunication channel has a higher quality of service than anon-exclusively-licensed communication channel. Also, two aggregatednon-exclusively-licensed communication channels can have two differentquality levels, such as when one is experiencing more interference thanthe other. In such examples, the communication channel having the lowerquality of service is selected for communicating a greater amount of theintegrated data.

Alternatively, and on the other hand, data can be primarily communicatedvia a non-exclusively-licensed communication channel so as to leave thelicensed communication channel open to communicate automatic retransmitrequests (ARQ) and acknowledgements (ACKs). This can reduce the numberof retransmissions while minimizing the data load and thus increasingthe apparent bandwidth capacity on the licensed communication channel.

In another example embodiment of channel aggregation, data for wirelesscommunication can be switched from one aggregated channel to another iftransmitting and/or receiving conditions change. For instance, data canbe communicated primarily via a non-exclusively-licensed communicationchannel but quickly switched to a aggregated, licensed communicationchannel if too much interference is encountered on thenon-exclusively-licensed communication channel or its quality otherwisedecreases.

As mentioned above, each AP 208(1-N) may be transmitting and/orreceiving the same data or each AP 208(1-N) may be transmitting and/orreceiving different data. When different data is being transmitted byAPs 208, there is an automatic capacity gain as each secondcommunication region 204 effectively becomes a mini-cell. With the samedata being transmitted by APs 208, capacity is not automaticallyincreased. However, a diversity gain can result, especially inoverlapping boundary regions such as boundary region 1010 (of FIG. 10).

As a subscriber station 104 roams throughout the licensed communicationcell 202, the aggregated licensed communication channel remainsconsistently supported by BTS 206 while the non-exclusively-licensedcommunication channel is supported by different APs 208 as thesubscriber station 104 moves from one non-exclusively-licensedcommunication region 204 to an adjacent region 204.

Generally, when the same data is being transmitted by each AP 208, thereare opportunities for statistical multiplexing gains and/or signal pathdiversity gains, especially when a subscriber station 104 is located ata boundary between two non-exclusively-licensed communication regions204(1-N), such as at boundary region 1010 betweennon-exclusively-licensed communication regions 204(3) and 204(4). Thereare also opportunities for diversity gains because multiple, up to allof, APs 208(1-N) can receive different versions of the same data from asubscriber station 104. These different versions can be combined usingany of a number of well known diversity combining mechanisms.

This capacity versus diversity gain implementation option is discussedbelow in the context of an example channel aggregation between alicensed and a non-exclusively-licensed channel. Usually,non-exclusively-licensed channels have a lower allowable transmit powerand are subject to increased interference relative to licensed channels.Overlaying a first communication region 202 with multiple secondcommunication regions 204 can effectively use the first issue tomitigate the second issue, as is described below.

In FIGS. 10 and 11, a cell 202 with a licensed BTS footprint has anunderlay comprised of multiple overlapping non-exclusively-licensed APfootprints (204) that are sufficient to substantially cover the licensedBTS footprint. In this example situation, instead of striving formaximum capacity in the non-exclusively-licensed spectrum, theidentified goals are increasing robustness and eliminating handoffbetween these smaller non-exclusively-licensed cells. For this example,it is given that there is channel aggregation of a single licensedchannel and a single non-exclusively-licensed channel under the controlof a single centralized MAC layer that can distribute trafficappropriately.

To pursue these two identified goals, the non-exclusively-licensed APsin the BTS footprint transmit the same data on the same channel. Any APthat hears a subscriber forwards the data up to the centralized MAC. Atthe boundaries (e.g., boundary 1010) of the non-exclusively-licensedcells, there is likely a diversity gain at the subscriber station'sreceive because it receives identical data from multiple APs with smalldifferences in arrival time. If properly constructed to do combining ata centralized location, the receiving APs can provide uplink diversitygain. Additionally, a MAC layer diversity gain can be achieved byreceiving multiple copies of the same protocol data unit (PDU) from thesubscriber station, which can be used to reduce the need for ARQretransmissions.

This diversity gain effectively enables the non-exclusively-licensedspectrum to be used for additional capacity. Once the additionalcapacity is achieved, it can be traded off for additional coverage byusing stronger codes to achieve robustness at greater distance with thenon-exclusively-licensed spectrum adding back the throughput that may belost. The stronger codes can be ones from a given standard, or, if thestandard is extensible, new codes can be utilized if wireless devices onboth ends of a link understand the new codes.

The description above presents the capacity increase versus a diversitygain tradeoff as if the only option is for all APs 208 to transmit thesame data or for all APs 208 to transmit different data. However, analternative implementation takes a middle ground. This alternativeentails selected APs 208 to be transmitting the same data while otherAPs 208 within cell 202 are transmitting different data. For example,with reference to FIG. 11, APs 208(2, 3, N) may be transceiving the samedata with subscriber station 104(1) while other APs (e.g., 208(1) and208(4-8)) may be transceiving different data. This enables somestatistical multiplexing through a subset of APs 208 and a capacity gainthrough other APs 208. It does entail some centralized coordinationand/or decentralized decision-making, for example using received signalstrength and or location techniques to determine which sets of APs 208are to communicate with which subscriber stations 104.

In short, when APs 208 transmit the same data and channels, there is noautomatic bulk capacity increase, but there can be a multiplexing and adiversity gain. Additionally, there are fewer handovers between APs 208,and a greater interference tolerance. When APs 208 transmit differentdata, there are no multiplexing or diversity gains, and there is anadded handover complexity. However, bulk capacity can be automaticallyincreased.

A capacity increase versus a diversity gain tradeoff implementationoption is described relatively qualitatively above. The bulk capacityincrease option involves a handover complexity when a subscriber station104 moves from one second communication region 204 to another secondcommunication region 204. The diversity gain option forfeits the bulkcapacity gain but avoids the handover complexity. This capacity increaseversus a diversity gain tradeoff issue is described below relativelyquantitatively.

Generally, increasing the capacity of a wireless system is advantageous.The following Equation 1 reflects a system's capacity and is termed theShannon capacity formula:

$\begin{matrix}{{C = {{BW}\;{\log_{2}( {1 + \frac{S}{1 + N}} )}}},} & ( {{Eqn}\mspace{14mu} 1} )\end{matrix}$Where S, I, and N denote signal (S), interference (I), and noise (N)power spectral densities, respectively. When the signal, interference,and noise are frequency dependent, the capacity formula becomes as shownin Equation 2:

$\begin{matrix}{C = {\int_{0}^{BW}{{\log_{2}( {1 + \frac{S(f)}{{I(f)} + {N(f)}}} )}.}}} & ( {{Eqn}\mspace{14mu} 2} )\end{matrix}$

From the formulas above, it is apparent that increasing system bandwidthcontributes linearly to the system capacity, whereas increasing thesystem's SINR contributes only logarithmically to the system capacity.Therefore, when more bandwidth is added to the system, whether as alicensed, non-exclusively-licensed, or other communication channel, theadditional bandwidth can be used to linearly increase the systemcapacity.

With respect to interference considerations, non-exclusively-licensedfrequency bands, such as the ISM band at 2.4 GHz may be initially viewedas having a lower capacity due to increased interference. In reality,however, cellular communication systems can suffer from high inter-cellinterference that can be only somewhat mitigated by interferencecancellation or interference avoidance schemes.

With respect to power considerations, ISM bands for point-to-pointcommunication are limited in the 2.4 GHz ISM band by the amount ofdirectional antenna gain. Practical systems may exhibit 42 dBm transmitpower, which is similar to the allowable power in licensed bands sansthe antenna gain. In the uplink, the power difference is essentiallynon-existent as mobile subscribers typically transmit up to 24 dBm,which is less than the FCC limit in most non-exclusively-licensed bands.Consequently, another option for allocating between two aggregatedchannels is: a non-exclusively-licensed band can be used for the uplinkto free-up the licensed band for downlink transmissions.

If a subscriber station 104 has multiple receive data paths and onetransmit data path (e.g., multiple receive chains and one transmittingchain), one of the data receive paths can be allocated to the licensedband and the other data receive path can be allocated to thenon-exclusively-licensed band given that the bands are not contiguous.Based on CINR measurements, a base station 102 can maximize capacity bydeciding how best to utilize the two receive chains. With two receivechains that are used in one band, on the other hand, a subscriberstation 104 can use maximum ratio combining (MRC) to reduce the requiredCINR and thus increase capacity whereas splitting each antenna fordifferent bands increases the available bandwidth.

The following metric can be used as presented in Equation 3:

$\begin{matrix}{\max\{ {{\int_{0}^{{BW}{(L)}}{\log_{2}( {1 + \frac{{{CINR}(L)}_{with}2{Rx}}{\Gamma}} )}},{{\int_{0}^{{BW}{(L)}}{\log_{2}( {1 + \frac{{{CINR}(L)}_{with}1{Rx}}{\Gamma}} )}} + {\int_{0}^{{BW}{({LE})}}{\log_{2}( {1 + \frac{{{CINR}({LE})}_{with}1{Rx}}{\Gamma}} )}}}} \}} & ( {{Eqn}\mspace{14mu} 3} )\end{matrix}$where BW(L) is the bandwidth of the licensed system and .GAMMA. is thegap from capacity that depends on the error correction capability of thesystem. Similarly, a subscriber station 104 with one transmit antennacan choose a band based on the metric presented in Equation 4 below:

$\begin{matrix}{\max\{ {{\int_{0}^{{BW}{(L)}}{\log_{2}( {1 + \frac{{CINR}(L)}{\Gamma}} )}},{\int_{0}^{{BW}{({LE})}}{\log_{2}( {1 + \frac{{CINR}({LE})}{\Gamma}} )}}} \}} & ( {{Eqn}\mspace{14mu} 4} )\end{matrix}$where CINR is measured in the uplink.

Other example channel aggregation implementations, including how datamay be directed to each of the multiple aggregated channels, aredescribed below. For example, real-time data such as VoIP can betransceived on a first aggregated channel while non-real-time data canbe transceived on a second aggregated channel. The first channel can bea licensed channel, and the second channel can be anon-exclusively-licensed channel, or vice versa. In an OFDMA-basedimplementation, non-Hybrid Automatic-Repeat-Request (non-HARQ)connections can be transceived on a first aggregated channel while HARQconnections can be transceived on a second aggregated channel. The firstchannel can be a licensed channel, and the second channel can be anon-exclusively-licensed channel, or vice versa.

As another channel aggregation example with at least first and secondaggregated channels, the first aggregated channel can include DL/UL mapsand/or control channels for both of the first and second aggregatedchannels. The second aggregated channel then need only include data inthe downlink. This may reduce the likelihood that a subscriber stationthat is not capable of channel aggregation can utilize either channel,especially the second aggregated channel that does not include a DL/ULmap and/or a control channel. The first and second aggregated channelsmay be non-adjacent.

As yet another channel aggregation example with at least first andsecond aggregated channels, the first aggregated channel can include anuplink portion while the second aggregated channel does not include anuplink portion. Both of the first and second aggregated channels includea downlink portion. These channels may be adjacent or nonadjacent. Thisexample implementation may be applied to broadcast scenarios in which itmay be beneficial to provide greater bandwidth for the downlinkcommunications relative to the uplink communications. Also, an oppositechannel-aggregation scenario may be implemented in which of twoaggregated channels, both channels have uplink portions, but one omitsthe downlink portion while the other includes it. Generally, otherchannel-aggregation scenarios may include alternative numbers ofchannels and combinations of uplink and downlink portions.

The devices, actions, aspects, features, functions, procedures, modules,schemes, approaches, architectures, components, etc. of FIGS. 1-11 areillustrated in diagrams that are divided into multiple blocks. However,the order, interconnections, interrelationships, layout, etc. in whichFIGS. 1-11 are described and/or shown are not intended to be construedas a limitation, and any number of the blocks can be modified, combined,rearranged, augmented, omitted, etc. in any manner to implement one ormore methods, apparatuses, systems, devices, procedures, media,arrangements, etc. for channel aggregation.

Moreover, although systems, apparatuses, devices, media, methods,procedures, techniques, schemes, approaches, arrangements, and otherimplementations have been described in language specific to structural,logical, algorithmic, and functional features and/or diagrams, it is tobe understood that the invention defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. A method of transmission in a base station, themethod comprising: transmitting first data on a first channel via afirst carrier to a first wireless device, the first channel comprisingmultiple subchannels, wherein the first channel is transmitted in afirst cell; transmitting second data on a second channel via a secondcarrier to the first wireless device, wherein the second channel istransmitted in a second cell, such that the first data and the seconddata are transmitted in a coordinated manner by aggregating the firstchannel and the second channel, the first wireless device supportingchannel aggregation; transmitting third data on the second channel viathe second carrier to a second wireless device, the second wirelessdevice not supporting channel aggregation; and transmitting fourth dataon the first channel via the first carrier to a third wireless device,the third wireless device not supporting channel aggregation; whereineach of the first channel and the second channel is formed so that thesecond wireless device is capable of initiating communication with thebase station via the second channel and the third wireless device iscapable of initiating communication with the base station via the firstchannel, wherein the first channel is located in a different band thanthe second channel, wherein the first channel and the second channel areprovided in a set of channels, and wherein each channel in the set ofchannels can be individually and simultaneously used by wireless devicesthat do not support channel aggregation and by wireless devices thatsupport channel aggregation.
 2. The method of claim 1, wherein thesecond channel comprises multiple subchannels.
 3. The method of claim 1,further comprising: dividing integrated data into the first data and thesecond data.
 4. The method of claim 1, wherein a first frequency of thefirst channel is adjacent to a second frequency of the second channel.5. The method of claim 1, wherein the first channel and the secondchannel are properly formed in accordance with at least onepredetermined wireless scheme that is selected from a group of wirelessschemes comprising: a time division duplexing, orthogonal frequencydivision multiple access (TDD OFDMA) scheme; a frequency divisionduplexing, OFDMA (FDD OFDMA) scheme; a frequency division duplexing(FDD) scheme; an orthogonal frequency division multiplexing (OFDM)scheme; a single carrier (SC) scheme; a time division multiplexing (TDM)scheme; and a time division, code division multiple access (TD-CDMA)scheme.
 6. A method of transmission in a base station, the methodcomprising: transmitting first data on a first channel via a firstcarrier to a first wireless device, wherein the first channel istransmitted in a first cell; transmitting second data on a secondnonadjacent channel via a second carrier to the first wireless device,wherein the second nonadjacent channel is transmitted in a second cell,such that the first data and the second data are transmitted in acoordinated manner by aggregating the first channel and the secondnonadjacent channel, the first wireless device supporting channelaggregation; transmitting third data on the second nonadjacent channelvia the second carrier to a second wireless device, the second wirelessdevice not supporting channel aggregation; and transmitting fourth dataon the first channel via the first carrier to a third wireless device,the third wireless device not supporting channel aggregation; whereineach of the first channel and the second nonadjacent channel is formedso that the second wireless device is capable of initiatingcommunication with the base station via the second nonadjacent channeland the third wireless device is capable of initiating communicationwith the base station via the first channel, wherein the first channelis located in a different band than the second nonadjacent channel,wherein the first channel and the second nonadjacent channel areprovided in a set of channels, and wherein each channel in the set ofchannels can be individually and simultaneously used by wireless devicesthat do not support channel aggregation and by wireless devices thatsupport channel aggregation.
 7. The method of claim 6, wherein the firstchannel is associated with a first power regulation constraint, and thesecond nonadjacent channel is associated with a second different powerregulation constraint.
 8. The method of claim 6, wherein the firstchannel operates in accordance with a first wireless scheme, and thesecond nonadjacent channel operates in accordance with a seconddifferent wireless scheme.
 9. The method of claim 6, wherein the firstchannel is more reliable than the second nonadjacent channel; andwherein the method further comprises: selectively allocating real-timedata to the first channel; and selectively allocating non-real-time datato the second nonadjacent channel.
 10. The method of claim 6, whereinthe first channel comprises a licensed channel, and the secondnonadjacent channel comprises a non-exclusively-licensed channel; andwherein the method further comprises: selectively allocating datacommunications to the second nonadjacent channel; and selectivelyallocating automatic retransmit request (ARQ)-related communications tothe first channel.
 11. A method of transmission in a base station, themethod comprising: transmitting first data on a first channel via afirst carrier to a first wireless device, wherein the first channel istransmitted in a first cell; transmitting second data on a secondchannel via a second carrier to the first wireless device, wherein thesecond channel is transmitted in a second cell, such that the first dataand the second data are transmitted in a coordinated manner byaggregating the first channel and the second channel, wherein the firstchannel is located in a different band than the second channel located,the first wireless device supporting channel aggregation; transmittingthird data on the second channel via the second carrier to a secondwireless device, the second wireless device not supporting channelaggregation; and transmitting fourth data on the first channel via thefirst carrier to a third wireless device, the third wireless device notsupporting channel aggregation; wherein each of the first channel andthe second channel is formed so that the second wireless device iscapable of initiating communication with the base station via the secondchannel and the third wireless device is capable of initiatingcommunication with the base station via the first channel, wherein thefirst channel and the second channel are provided in a set of channels,and wherein each channel in the set of channels can be individually andsimultaneously used by wireless devices that do not support channelaggregation and by wireless devices that support channel aggregation.12. The method of claim 11, wherein the first channel is formed via aseparate Fast Fourier Transform (FFT) than the second channel.
 13. Themethod of claim 11, wherein: the transmitting first data on the firstchannel via the first carrier comprises transmitting the first data onthe first channel via the first carrier in accordance with a firstwireless scheme; and the transmitting second data on the second channelvia the second carrier comprises transmitting the second data on thesecond channel via the second carrier in accordance with a secondwireless scheme that differs from the first wireless scheme.
 14. Themethod of claim 11, wherein the first channel includes a first channelmapping, and the second channel includes a second channel mapping.
 15. Amethod of transmission in a base station, the method comprising:directing first data toward a first channel based on a firstcharacteristic of the first channel; directing second data toward asecond channel based on a second characteristic of the second channel;transmitting to a first wireless device the first data on the firstchannel via a first carrier, wherein the first channel is transmitted ina first cell; transmitting to the first wireless device the second dataon the second channel via a second carrier, wherein the second channelis transmitted in a second cell, such that the first data and the seconddata are transmitted in a coordinated manner by aggregating the firstchannel and the second channel, the first wireless device supportingchannel aggregation; transmitting third data on the second channel viathe second carrier to a second wireless device, the second wirelessdevice not supporting channel aggregation; and transmitting fourth dataon the first channel via the first carrier to a third wireless device,the third wireless device not supporting channel aggregation; whereineach of the first channel and the second channel is formed so that thesecond wireless device is capable of initiating communication with thebase station via the second channel and the third wireless device iscapable of initiating communication with the base station via the firstchannel, wherein the first channel is located in a different band thanthe second channel, wherein the first channel and the second channel areprovided in a set of channels, and wherein each channel in the set ofchannels can be individually and simultaneously used by wireless devicesthat do not support channel aggregation and by wireless devices thatsupport channel aggregation.
 16. The method of claim 15, wherein thefirst channel corresponds to a first maximum regulated power level, andthe second channel corresponds to a second maximum regulated powerlevel.
 17. The method of claim 15, wherein the first channel has ahigher signal-to-interference noise ratio (SINR) level than the secondchannel.
 18. The method of claim 15, wherein the first channel comprisesa licensed channel, and the second channel comprises anon-exclusively-licensed channel; and wherein: the directing first datatoward a first channel further comprises selectively directing automaticretransmit request (ARQ) data toward the first channel based on thefirst channel comprising the licensed channel; and the directing seconddata toward a second channel further comprises selectively directinggeneral data toward the second channel based on the second channelcomprising the non-exclusively-licensed channel.
 19. The method of claim15, wherein the first channel has a reliability that is higher than areliability of the second channel; and wherein: the directing first datatoward the first channel comprises selectively directing real-time datatoward the first channel based on the reliability of the first channel;and the directing second data toward the second channel comprisesselectively directing non-real-time data toward the second channel basedon the reliability of the second channel.
 20. The method of claim 1,wherein each of the first channel and the second channel areindependently and properly formed.
 21. The method of claim 6, whereineach of the first channel and the second nonadjacent channel areindependently and properly formed.
 22. The method of claim 11, whereineach of the first channel and the second channel are independently andproperly formed.
 23. The method of claim 15, wherein each of the firstchannel and the second channel are independently and properly formed.24. The method of claim 1, wherein the first channel is formed via aseparate Fast Fourier Transform (FFT) than the second channel.
 25. Themethod of claim 6, wherein the first channel is formed via a separateFast Fourier Transform (FFT) than the second nonadjacent channel. 26.The method of claim 15, wherein the first channel is formed via aseparate Fast Fourier Transform (FFT) than the second channel.